Low temperature rendering processes have been used to separate protein from fatty tissue in animal trimmings. Low temperature rendering processes are described in, for example, U.S. Pat. Nos. 3,008,831; 3,020,160; and 3,078,165. The processes generally involve comminuting fatty tissue from animals, such as hogs or cattle, to form a semi-solid slurry or meat emulsion, heating the slurry or emulsion to melt the fat, and then separating the fat and protein by centrifugation. The protein can then be used as an ingredient in processed meat products such as sausage and other cured and processed meats.
As reported in U.S. Pat. No. 3,219,616 to Brissey, it has been found that the protein or meat provided by prior art low temperature rendering processes suffer from undesirable flavor changes shortly after production. In order to reduce the flavor changes after low temperature rendering processes, this patent teaches using a heme-conditioning agent which reacts or combines with the heme pigments of the meat to reduce the activity of the heme pigments which catalyzes the development of off-flavor.
The government provides that a certain quality of meat product obtained from animal trimmings can be used undeclared in meat products of the same species. For example, "finely textured beef" and "lean finely textured beef" can be used in ground beef without being declared on the label. "Finely textured meat" is required to have a fat content of less than 30%; a protein content of greater than 140%, by weight; a protein efficiency ratio (PER) of 2.5 or higher, or an essential amino acids (EAA) content of 33% of the total amino acids or higher; must be prepared in a federally inspected plant; must not have a product temperature during processing exceeding 110.degree. F.; must be frozen in less than 30 minutes after processing; must not allow a significant increase in bacterial numbers; and must not be treated with chemicals or additives. "Lean finely textured meat" is required to have a fat content of less than 10%, by weight, and complies with the other requirements of "finely textured meat."